1. Field of the Invention
The present invention relates to a method and apparatus for recording new data in a writable disk after a previous recording to the disk is interrupted abnormally.
2. Description of the Related Art
FIG. 1 is a simplified block diagram of a conventional optical disk device for recording and reproducing data to/from a writable disk such as an once-recordable disk CD-R and a rewritable disk CD-RW. The disk device of FIG. 1 comprises a digital recording signal processor 4b for converting input data into recording-formatted data by adding additional data such as error correction codes, a channel bit encoder 11 for converting the recording-formatted data into EFM-formatted bit stream, a writing driver 12 for yielding a writing current according to an input bit stream, an optical pickup 2 for recording signals corresponding to the writing current onto an optical disk 1 and reproducing recorded signals from the optical disk 1, an R/F unit 3 for yielding servo error signals TE and FE, and binary signals through combining the reproduced signals from the disk 1, a digital reproducing signal processor 4a for restoring original data from the binary signals, a sled motor 9 for moving the pickup 2 radially, a spindle motor 10 for rotating the disk 1, a driving unit 8 for driving the motors 9 and 10, a servo unit 5 for controlling the driving unit 8 and the pickup 2 based on the servo error signals TE and FE, a microcomputer 6 for controlling the overall operation of the servo unit 5, the digital signal processors 4a and 4b, and the writing driver 12 in order to record and reproduce data, and a memory 7 for storing data for the microcomputer 6 to use for supervising operations.
FIGS. 2 and 3 depict a recording area format and an example of recorded data for an once-recordable disk CD-R or a rewritable disk CD-RW. The writable disk is partitioned, as shown in FIG. 2, into a power calibration area (PCA), a program memory area (PMA), and one or more sessions, each consisting of a lead-in area, a program area, and a lead-out area.
The PCA is used for writing data experimentally to determine an optimal writing power, and the PMA is reserved for recording information such as position and size of each recorded track which is data group recorded continuously without stop. Each track recorded in the program area is separated by a pause section which is corresponding to about 2 second reproduction time.
The lead-in area has information on the next recording position, that is, a lead-in area position of the neighboring next session. Therefore, when data recording is requested, a final recording position, that is, the next recordable position is detected easily and quickly through reading the lead-in area of a last session which was closed before.
FIG. 4 is a flow chart illustrating a process of writing new data adjacently to previously-recorded data. The conventional data writing method of FIG. 4 to be conducted by the disk device of FIG. 1 is described.
When a user requests new data to be recorded in an inserted disk 1, the microcomputer 6 sets its mode to the recording mode (S10), conducts an optimal power calibration (OPC) by recording and reproducing test data to/from the PCA, and sets an optimal writing power determined through the OPC into the writing driver 12 (S11).
After that, the microcomputer 6 reads position and size information, which is recorded in the PMA, about recorded tracks (S12), and searches for the first lead-in area, the second lead-in area, and the third lead-in area, in turn based on the PMA information (S13). For example, suppose that tracks 1 and 2 belong to the first closed session, tracks 3 and 4 belong to the second closed session, and tracks 5 and 6 are recorded next to the second closed session as shown in FIG. 5. The microcomputer 6 reads out position information of the second lead-in area ‘LIA1’ from the first lead-in area ‘LIA1’, and reads the second lead-in area ‘LIA1’ to know the next recording position, that is, the position of track 5.
Since the program area containing the tracks 5 and 6 is not closed into a session (S14), the microcomputer 6 examines the PMA information to know how many tracks are recorded in the disk 1 (S15), and locates final recorded track 6 based on the PMA information (S16). Then, the microcomputer 6 controls the digital recording signal processor 4b and the servo unit 5 to record new data on an area separated by a pause section from track 6. If all of the new data are recorded, the microcomputer 6 designates just-recorded data block as track 7, creates information on the recorded position and size about the track 7 and writes it in the PMA (S17).
Some time later, if the tracks 5 to 7 are requested to be closed in a session (S18), the microcomputer 6 groups the tracks 5 to 7 into the third session, writes necessary information in the secured third lead-in area ‘LIA3’, and secures the third lead-out area ‘LOA3’ next to the last track (S19). After that, the above-explained recording operation will be conducted or not according to a user's request.
However, during the recording operation, a servo control may fail due to a mechanical shock or a data buffer may be underrun, which causes the current recording operation to stop abruptly without writing track information or lead-in information. Therefore, the PMA information may represent real-recorded tracks wrongly or the lead-in area may contain invalid information.
For a writable disk suffering from such a recording failure, it is impossible to detect the last recorded position accurately. As a result, new data may be overwritten onto previous data or unwritten area may arise between the last recorded track and the new recorded track. If previous data was overwritten by the new data, the previous data would be lost.
Especially, if the writable disk is once-writable one, the new recorded data as well as the previous data are damaged together when the previous data are overwritten since the surface is burned while recording and it can not be restored to the unburned state.